Method for manufacturing a bipolar plate of a fuel cell and bipolar plate

Abstract

Method for manufacturing a bipolar plate of a fuel cell, comprising at least two partial plates (1, 2) which are connected to each other at least at the edges, wherein: a recess (1.1, 2.1) is provided around the perimeter of both partial plates (1, 2) and the partial plates (1, 2) are arranged such that a first recess (1.1) of a first partial plate (1) projects into a second recess (2.1) of a second partial plate (2), wherein an outer surface (A) of the first recess (1.1) is partially in contact with an inner surface (I) of the second recess (2.1); a joining material (4) is applied to the outer surface (A) of the first recess (1.1) and / or to the inner surface (I) of the second recess (2.1) in such a way that, after the partial plates (1, 2) are arranged together, the joining material (4) is located in a cavity (H) bounded by the outer surface (A) of the first recess (1.1), the inner surface (I) of the second recess (2.1) and by the contact areas, wherein the joining material forms a seal so that any gaps between the two partial plates (1, 2) are sealed against the environment; The recesses are provided in such a way that the subplates center themselves through the recesses when the bipolar plate is assembled, the angles of the walls (1.1.2, 2.1.2) of both subplates (1, 2) that laterally delimit the respective recess (1.1, 2.1) are predetermined depending on each other, so that at least a maximum dimension with regard to the projection of the first recess (1.1) into the second recess (2.1) is predetermined; and the contact areas are formed by the outer surface (A) being in contact with the inner surface (I) in the area of ​​the laterally bounding walls (1.1.2, 2.1.2) of both partial plates (1, 2).

Description

[0001] The invention relates to a method for manufacturing a bipolar plate for a fuel cell, comprising at least two partial plates which are joined together at least at their edges. The invention further relates to a bipolar plate manufactured by the method.

[0002] From DE 102 51 775 A1, a method for joining at least two plate elements of a fuel cell unit is known. In this method, a radiation-activated adhesive is applied to at least one of the at least two plate elements. The adhesive is irradiated for a predetermined period, and the at least two plate elements are arranged in the desired joining position and joined under pressure and / or heat. The method is used, for example, in the production of fuel cell stacks.

[0003] Furthermore, a bipolar plate assembly comprising a pair of plates, an electrically conductive layer, and a fluid seal is known from DE 11 2004 000 147 T5. The plate pair has facing plate surfaces, each of which comprises an inner section and an outer circumferential section. Each inner section has an alternating plurality of both coolant grooves and coolant ribs formed thereon. The electrically conductive layer is deposited over at least the coolant ribs of each plate. The facing plate surfaces are connected to form both a plurality of electrical connecting lines between the respective facing pairs of coolant ribs and a plurality of coolant channels between the respective facing pairs of coolant grooves.The fluid seal is arranged between the inner section and the circumferential section of the facing plate surfaces, with the fluid seal surrounding each inner section.

[0004] Furthermore, DE 11 2004 000 147 T5 describes a fuel cell stack with a plurality of membrane electrode assemblies arranged in a stacked configuration and a bipolar plate assembly positioned between respective pairs of membrane electrode assemblies. Each bipolar plate assembly comprises a pair of aligned plates, each of which has a plurality of reactant gas channels on a first plate surface facing the membrane electrode assemblies and a plurality of alternating coolant grooves and ribs on a second plate surface facing away from the membrane electrode assemblies. The second plate surface has an electrically conductive layer deposited at least over the coolant ribs.The bipolar plate assembly is connected to form a multitude of electrical connections between opposing pairs of coolant ribs, as well as a multitude of coolant channels between opposing pairs of coolant grooves. A fluid seal surrounds the coolant channels and coolant ribs of each bipolar plate assembly to isolate the reactant gas channels from the electrically conductive layer. Furthermore, a method for isolating reactant gas passages from coolant-contacting surfaces in a fuel cell stack is described.

[0005] Document DE 10 2007 025 479 A1 relates to a single fuel cell for a fuel cell stack, comprising a cell unit consisting of a gas-permeable substrate and a cathode-anode unit mounted on it, which is supported by a bipolar plate. The bipolar plate consists of a lower shell formed from a metal sheet and an upper shell, also formed from a metal sheet, which is mounted on the lower shell to form a cavity. The upper shell has a passage window for the gas from the cavity to the cell unit. The cell unit is ultimately gas-tightly connected to the upper shell on the side facing away from the cavity by means of an interposition material. The cell unit, with the interposition material, is located within a frame that is essentially L-shaped in cross-section. This frame is either formed into the upper shell or is a separate component gas-tightly connected to it.The edge sections, with which several individual fuel cells are stacked on top of each other with an intermediate layer of a second joining material, are essentially provided all around with grooves and protrusions, such that a protrusion in the lower shell of a first individual fuel cell, with the intermediate layer of the second joining material, projects into a groove in the upper shell of a second individual fuel cell.

[0006] Document DE 10 2005 046 461 A1 relates to a fuel cell arrangement comprising at least one bipolar plate layer and an adhesive partner - preferably an electrode membrane unit, wherein the adhesive partner is bonded to the bipolar plate layer with an adhesive material or a physically setting adhesive located on a three-dimensional sealing structure of the bipolar plate layer and / or adjacent edge area of ​​the bipolar plate layer.

[0007] Document JP 2012-016877 A relates to a mold for casting a fuel cell gasket for integrally casting a gasket onto a fuel cell component element with a shape corresponding to the gasket, wherein a cavity into which a mold material of the gasket can be introduced, and a venting part which is provided to be in contact with the cavity, and which guides the excess mold material which is introduced into the cavity outside the cavity as a passage.

[0008] Document DE 10 2005 020332 A1 relates to a supply plate (1), a base plate for constructing such a supply plate, and a method for manufacturing a supply plate for electrochemical systems. Two base plates (2a, 2b) are thermally joined together using an adhesive (3), wherein this adhesive (3) has a lower melting point than the material of the base plates (2a, 2b). At least one first base plate (2a) has at least one pocket (4a) into which adhesive is poured, and subsequently the second base plate (2b) is placed onto a joining surface (F) of the first plate, and the base plates (2a, 2b) are joined by applying heat to the adhesive.

[0009] The invention is based on the objective of providing a method for manufacturing a bipolar plate of a fuel cell and such a bipolar plate, which is improved compared to the prior art.

[0010] The object of the invention is achieved with regard to the method by the features specified in claim 1 and with regard to the bipolar plate by the features specified in claim 7.

[0011] Advantageous embodiments of the invention are the subject of the dependent claims.

[0012] A method for manufacturing a bipolar plate of a fuel cell, comprising at least two sub-plates, provides that the sub-plates are connected to each other, at least at their edges. According to the invention, a recess is formed circumferentially in both sub-plates at their edges, and the sub-plates are arranged such that a first recess of a first sub-plate projects into a second recess of a second sub-plate, wherein an outer surface of the first recess is in contact with an inner surface of the second recess in certain areas.

[0013] Each of the two sub-plates has a recess, allowing the plates to self-center advantageously during assembly of the bipolar plate. The angles of the walls of both sub-plates, which laterally define each recess, are mutually dependent, thus specifying at least a maximum dimension for the insertion of the first recess into the second. The positioning of the two sub-plates relative to each other is predetermined by the two recesses, as the first recess fits into the second recess during assembly. Therefore, the two recesses act as an assembly aid for the bipolar plate, thereby reducing the time and costs associated with its production.

[0014] A joining material is applied to the outer surface of the first recess and / or to the inner surface of the second recess in such a way that, after the partial plates have been arranged next to each other, the joining material is located in a cavity bounded by the outer surface of the first recess, the inner surface of the second recess and by the contact areas.

[0015] Furthermore, the joining material preferably forms a seal, so that any gaps between the two partial plates are sealed against the environment.

[0016] The contact areas are formed by the outer surface touching the inner surface in the area of ​​the laterally bounding walls of both partial plates.

[0017] The cavity advantageously provides a receiving area for the joining material, enabling the two partial plates to be bonded together. The circumferential connection point formed by the recesses around the edge of the two adjacent partial plates is particularly preferably designed to be medium-tight.

[0018] Because the connection point is designed to be so tight, channels, for example for coolant flow, which are formed by shapes in the partial plates and the arrangement of them, can be designed to be correspondingly narrow and deep.

[0019] This allows the efficiency of the fuel cell to be increased, since the bipolar plate formed by the two sub-plates has improved electrical characteristics.

[0020] Particularly preferred is the application of a solder and / or an adhesive as a joining material to the outer surface of the first recess and / or to the inner surface of the second recess, so that the two partial plates are bonded together and the joint is thereby sealed particularly advantageously.

[0021] Furthermore, it is provided that a sealing material is applied to a sealing section extending on the side of the first recess of the first sub-plate and / or the second recess of the second sub-plate facing away from the joining material. This sealing material is applied to seal a connection point between adjacent bipolar plates for the formation of a fuel cell stack, thereby increasing the efficiency of the fuel cell or fuel cells.

[0022] In a particularly advantageous embodiment, the sealing material is hot-sprayed onto the sealing section or sections, so that the heat of the hot sealing material, which is absorbed in the respective sealing section and thereby transferred to the cavity in which the joining material is arranged, activates the adhesive and / or the solder for the material-bonded connection of the partial plates.

[0023] If the sealing material is hot-sprayed, one work step – namely, heating, or at least heating the subplates in the area of ​​the recesses from the outside – can be eliminated. This results in a significant time saving and therefore also a cost saving in the production of a bipolar plate.

[0024] Alternatively or additionally, the partial plates can also be heat-treated to melt the joining material arranged in the cavity, whereby at least one preheated, preferably heatable, tool can be used for this purpose. In an advantageous embodiment, a contact pressure can simultaneously be exerted on the partial plates in the area of ​​the recesses by means of such a tool.

[0025] In addition to activating the joining material with heat, a contact pressure is simultaneously applied to the two partial plates to create the material-bonded connection and to ensure the resulting seal at the joint. The contact pressure acting on the partial plates is advantageously limited by the areas of the partial plates adjacent to the recesses on both sides, since these areas of the two partial plates are in contact with each other.

[0026] If the contact pressure is applied to the sub-plates by means of the tool as described above, the tool can preferably be adjusted with regard to the contact pressure to be applied. Preferably, the contact pressure is set only so high that material failure of the two sub-plates in the area of ​​the recesses can be largely ruled out.

[0027] In a particularly advantageous embodiment of the method, a number of vent holes and / or vent slots are provided in an area of ​​the first partial plate and / or the second partial plate adjacent to the first recess and / or to the second recess, which can be fluidically connected to the cavity formed between the outer surface of the first recess and the inner surface of the second recess and the contact areas in order to allow the joining material, in particular the adhesive, to evaporate.

[0028] These vent holes and / or vent slots serve in particular to vent the cavity, since pressing the first recess into the second recess displaces air which could not escape without the vent holes and / or vent slots, and thus there could be a risk that the material bond and therefore the seal between the two partial plates in the area of ​​the recesses cannot be ensured.

[0029] Furthermore, the invention relates to a bipolar plate, which is manufactured according to the method described above and is formed from the two sub-plates. The sub-plates have a circumferential recess around their edges, and the sub-plates are arranged such that a first recess of a first sub-plate projects into a second recess of a second sub-plate, with an outer surface of the first recess partially contacting an inner surface of the second recess.

[0030] A cavity is formed between an outer surface of the first recess, an inner surface of the second recess, and the contact areas. A bonding material is arranged within this cavity, enabling the two sub-plates to be joined together by means of a material-fit connection. This bonding material forms a seal, thus sealing any gaps between the two sub-plates from the environment. The projection of the first recess into the second recess creates a self-centering effect between the two sub-plates. The angles of the walls of both sub-plates, which laterally define the respective recesses, are mutually dependent, such that at least a maximum projection of the first recess into the second recess is predetermined. The contact areas are formed by the contact of the outer surface against the inner surface in the region of the laterally defining walls of both sub-plates.

[0031] By means of such a formed bipolar plate, the performance of the bipolar plate within a fuel cell can be increased, since the depressions provide the possibility of efficient sealing of the bipolar plate against its environment.

[0032] A cavity is formed between an outer surface of the first recess, an inner surface of the second recess, and the contact areas. A bonding material is placed in this cavity, enabling the two partial plates to be joined together. This bonding material advantageously serves both as a material-bonded connection and as a seal in the area where the two partial plates are joined.

[0033] In an advantageous embodiment of the bipolar plate produced by means of the two partial plates, an edge region of the first partial plate and / or the second partial plate adjacent to the first depression and / or the second depression has a number of vent holes and / or vent slots which are fluidically connected to the cavity formed between the outer surface of the first depression and the inner surface of the second depression and the contact areas.

[0034] These ventilation holes and / or slots are designed, for example, to allow air displaced when the two plates are pressed together to escape, thus ensuring a seal at the joint between the two plates in the area of ​​the recesses. Furthermore, the ventilation holes and / or slots also allow the adhesive used as a bonding agent to evaporate.

[0035] Exemplary embodiments of the invention are explained in more detail below with reference to drawings.

[0036] This shows: Fig. 1 schematically a cross-sectional view of an edge area of ​​a bipolar plate formed by means of two attached partial plates for a fuel cell, Fig. 2 schematically the sectional view according to Fig. 1 with sealing material in the compressed state, Fig. 3 schematically a cross-sectional view of the edge area of ​​the bipolar plate formed by means of two attached partial plates in the area of ​​a ventilation slot, Fig. 4 schematically a sectional view of an alternative embodiment of the edge region of the bipolar plate with formed stiffeners, Fig. 5 schematically a sectional view of another alternative embodiment of the edge region of a bipolar plate for a fuel cell, Fig. 6 schematically shows an edge area of ​​the bipolar plate in the area of ​​shaped ventilation slots and Fig. 7 schematically a top view of a tool for manufacturing a bipolar plate for a fuel cell.

[0037] Corresponding parts are marked with the same reference symbols in all figures.

[0038] In Fig. Figure 1 shows a cross-sectional view of the edge areas of two attached sub-plates 1, 2, by means of which a bipolar plate (not shown) for a fuel cell is formed.

[0039] A first partial plate 1 forms the anode and a second partial plate 2 forms the cathode of the bipolar plate, with an inner plate 3 arranged between the two partial plates 1, 2 facing away from the edge areas.

[0040] The two partial plates 1, 2 each have a groove-shaped depression 1.1, 2.1 extending completely around their edge area, which is introduced into the respective partial plate 1, 2, for example, in a deep drawing and / or stretch drawing process.

[0041] The recesses 1.1, 2.1 are placed in the sub-plates 1, 2 in their respective positions for assembly in the same orientation, so that a first recess 1.1 of the first sub-plate 1 protrudes into a second recess 2.1 of the second sub-plate 2.

[0042] The first recess 1.1 of the first partial plate 1 is shaped such that a section 1.1.1 opposite the opening runs largely straight. The walls 1.1.2 laterally bounding the first recess 1.1 are slightly chamfered, with the walls 1.1.2 being of unequal height.

[0043] A section 2.1.1 opposite the opening of the second recess 2.1 has opposing bulges 2.1.1.1 at its edges, such that the side walls 2.1.2 are longer compared to the side walls 1.1.2 of the first recess 1.1. A wall 1.1.2 facing away from the edge is less high than the opposite wall 2.1.2 of the second recess 2.1, so that areas 2.2 of the second subplate 2 immediately adjacent to the recess 2.1 run in different planes that are arranged parallel to each other.

[0044] Regarding the first subplate 1, areas 1.2 adjacent to the first depression 1.1 run parallel to each other in different planes.

[0045] The walls 1.1.2, 2.1.2 of the two recesses 1.1, 2.1 are of different heights, since, as described above, the inner plate 3 is arranged between the partial plates 1, 2.

[0046] In the manufacture of the bipolar plate, a joining material 4, for example an adhesive and / or a solder, is applied to an outer surface A of the section 1.1.1 of the first recess 1.1 opposite the opening and / or to an inner surface I of the section 2.1.1 of the second recess 2.1 opposite the opening. The adhesive is preferably a polymer that is activated by heating, and the solder is a material for low-temperature soldering, wherein low-temperature soldering is carried out in a temperature range of 400° to 500°.

[0047] Subsequently, the two partial plates 1, 2 are arranged such that the first recess 1.1 projects into the second recess 2.1. This arrangement of the two partial plates 1, 2 creates a cavity H by means of an outer surface A of the first recess 1.1, an inner surface I of the second recess 2.1, and contact areas formed by the outer surface A against the inner surface I. The joining material 4 is located in this cavity H after the two partial plates 1, 2 have been arranged together.

[0048] The angles of the walls 1.1.2, 2.1.2 of both subplates 1, 2, which laterally delimit the respective recesses 1.1, 2.1, are mutually dependent, so that at least a maximum dimension regarding the projection of the first recess 1.1 into the second recess 2.1 is specified. In particular, a specified nesting angle α of the first subplate 1 corresponds to a specified clearance angle β of the second subplate 2, such that the first recess 1.1 projects into the second recess 2.1 of the second subplate 2 only up to the specified dimension.

[0049] The first partial plate 1 has a sealing section D for applying a sealing material D1, wherein the sealing section D is located on a side of the first recess 1.1 facing away from the joining material 4. The sealing material D1 is arranged in the first recess 1.1 with respect to the first partial plate 1.

[0050] A sealing section D of the second partial plate 2 is arranged on a side of the second recess 2.1 facing away from the joining material 4. The sealing section D is applied between the two protrusions 2.1.1.1 of the section 2.1.1 opposite the opening of the second recess 2.1.

[0051] A different sealing material D2 is applied to the sealing section D of the first recess 1.1 than to the sealing section D of the second recess 2.1, whereby it may also be provided that the same sealing material D1, D2 is applied to both sealing sections D.

[0052] The bipolar plate formed by the two materially bonded subplates 1, 2 is part of a fuel cell stack (not shown), wherein a further subplate 1, 2 (not shown) is arranged adjacent to the first subplate 1 and the second subplate 2. Adjacent to the first subplate 1 is a second subplate 2 (not shown) of another bipolar plate, and adjacent to the second subplate 2 is a first subplate 1 (not shown) of another bipolar plate.

[0053] By arranging the bipolar plate formed by the two partial plates 1, 2 in a fuel cell stack, the sealing materials D1, D2 arranged at the intended sealing sections D of the recesses 1.1, 2.1 are compressed, as shown in Fig. 2 is represented by the dashed line.

[0054] Fig. Figure 3 shows a cross-sectional view of the edge region of the bipolar plate formed by the two sub-plates 1, 2, with a ventilation option formed at the edge in the form of a ventilation slot E, which is located in Fig. 6 is shown in detail.

[0055] In the area of ​​the vent slot E, the walls 1.1.2, 2.1.2 which laterally bound the respective recess 1.1, 2.1 are essentially of the same height, so that the areas 1.2, 2.2 of the two subplates 1, 2 facing the edge area of ​​the bipolar plate and adjacent to the recess 1.1, 2.1 are spaced apart from each other.

[0056] Alternatively, the venting option can be designed as a vent hole, the venting option serving to vent the joining material 4, in particular the adhesive, during a joining process, i.e., during a material-bonded connection of the two sub-plates 1, 2. The joining material 4, in particular the adhesive, can efficiently evaporate through the vent slot E during curing.

[0057] At least two alternatives are provided for the material-bonded fastening of the two partial plates 1, 2 to each other.

[0058] In a first alternative, the sub-plates 1, 2 are arranged adjacent to one another such that the first recess 1.1 of the first sub-plate 1 projects into the second recess 2.1 of the second sub-plate 2 up to the specified dimension, with the joining material 4 located in the cavity H between the outer surface A of the first recess 1.1 and the inner surface I of the second recess 2.1 and the contact areas of the walls 1.1.2, 2.1.2. The recesses 1.1, 2.1 thus serve as an assembly aid for arranging the two sub-plates 1, 2 adjacent to one another, as the sub-plates 1, 2 self-center by means of the recesses 1.1, 2.1.

[0059] According to the first alternative, the respective sealing material D1, D2 is hot-sprayed onto the respective sealing section D, whereby the heat of the sealing material D1, D2 is absorbed by the two partial plates 1, 2 in the sealing section D, transferred into the cavity H and thus supplied to the joining material 4, whereby the adhesive polymerizes as joining material 4.

[0060] The applied heat melts, i.e., activates, the joining material 4 in the form of adhesive and / or solder, so that the two partial plates 1, 2 are bonded together via the recesses 1.1, 2.1. The viscosity of the joining material 4 decreases upon application of heat, causing it to spread within the cavity H. Preferably, in the first alternative, only adhesive is used as the joining material 4, allowing the process steps of bonding and spraying the sealing material D1, D2 to be carried out simultaneously in a single process step.

[0061] The two subplates 1, 2 are pressed together, with the maximum contact pressure limited by the areas 1.2, 2.2 of the subplates 1, 2 that are directly adjacent to the recesses 1.1, 2.1. When the areas 1.2, 2.2 adjacent to the recesses 1.1, 2.1 are in contact with each other, optimal positioning of the two subplates 1, 2 for forming the bipolar plate is largely achieved.

[0062] Further increased pressure would very likely result in material failure of at least one of the two sub-plates 1, 2, particularly in the area of ​​the recesses 1.1, 2.1.

[0063] When pressure is applied to the partial plates 1, 2 in the area of ​​the recesses 1.1, 2.1, the heated joining material 4 distributes itself in the cavity H depending on its quantity, whereby the volume of the cavity H can decrease when the two partial plates 1, 2 are pressed against each other. The bulges 2.1.1.1 formed in the second recess 2.1 create a reservoir R when the partial plates 1, 2 are pressed against each other, in which excess joining material 4 can collect, as shown in Fig. 4 is shown in more detail.

[0064] The joining material 4 is arranged in the cavity H and is distributed within it, so that the two partial plates 1, 2 are joined together by means of the joining material 4 in a material-locking manner and, if necessary, by means of the first recess 1.1 protruding into the second recess 2.1 in a form-locking manner.

[0065] In this process, the joining material 4 forms a seal within a connection point of the two partial plates 1, 2 in the area of ​​the recesses 1.1, 2.1, in addition to the material-bonded fastening.

[0066] The second possible alternative for fastening the two partial plates 1, 2 to each other provides that the joining material 4 is applied using at least one preheated tool 5, which is exemplified in Fig. 7 is shown, is heated and thus activated, with the tool 5 preferably being heatable.

[0067] If solder is used as the joining material 4, a tool 5 used is preferably a continuous furnace, which is not shown in detail.

[0068] Furthermore, it can be provided that the tool 5 is preferably designed such that the partial plates 1, 2 to be attached to one another are pressed together by means of the tool 5, whereby the joining material 4 is activated and at the same time a pressing force is exerted on the partial plates 1, 2 to form a material-locking connection.

[0069] If the two partial plates 1, 2 are bonded together in the area of ​​the recesses 1.1, 2.1, the respective sealing material D1, D2 is applied to the sealing sections D in the area of ​​the recesses 1.1, 2.1, whereby, in the second possible alternative, the respective sealing material D1, D2 is not applied hot to the sealing sections D. The sealing material(s) D1, D2 are applied to the sealing sections D, in particular, after the bonding, if only solder is used as the joining material 4.

[0070] In Fig. Figure 4 shows an alternative embodiment with regard to the design of an edge region of a bipolar plate formed by means of the two partial plates 1, 2.

[0071] The diagram shows the edge region in the area of ​​a ventilation slot E, where stiffeners V are preferably formed, particularly for stiffening the edge region. The stiffeners V are shown only schematically. Preferably, a plurality of stiffeners V are formed in the edge region, arranged at regular intervals from one another.

[0072] Fig. Figure 5 shows another alternative embodiment of the edge region of a bipolar plate formed by means of the two partial plates 1, 2.

[0073] As in the previous embodiments, the first recess 1.1 of the first partial plate 1 projects into the second recess 2.1 of the second partial plate 2 to the specified dimension for fastening the two partial plates 1, 2 to each other.

[0074] In this embodiment, the first recess 1.1 of the first partial plate 1 has bulges 1.1.1.1 formed as caverns opposite each other. The second recess 2.1 of the second partial plate 2 has, in the sectional view, essentially the cross-section of a right truncated cone.

[0075] In the area of ​​a bulge 1.1.1.1 of the first recess 1.1, facing away from the edge, a through hole L is provided in the second recess 2.1 as a vent hole, by means of which air is prevented from being trapped within the bulges 1.1.1.1. The sealing material D2 applied to the sealing section D of the second subplate 2 can flow through the hole L into the bulge 1.1.1.1, thereby displacing any trapped air. The bulges 1.1.1.1 formed in the first recess 1.1 constitute, on the one hand, the cavities and, on the other hand, a stiffening structure in the area of ​​the recesses 1.1, 2.1 of both subplates 1, 2.

[0076] By means of the hole L in the second recess 2.1 of the second partial plate 2 and the flow-related connection to the area of ​​the first recess 1.1, it is also possible to inject one of the sealing materials D1, D2, for example, from one sealing section D to the opposite sealing section D or vice versa.

[0077] In Fig. Figure 6 shows an edge region of the bipolar plate, which is formed from the two partial plates 1, 2 which are bonded together.

[0078] The regularly spaced ventilation slots E are shown in detail, wherein the ventilation slots E are formed in particular by partial shapings of the second subplate 2.

[0079] The vent slots E are fluidically connected to the cavity H (not shown), with the fluidic connection being realized in the direction of the edge region of the bipolar plate formed by means of the sub-plates 1, 2.

[0080] The vent slots E or alternatively the vent holes are preferably designed in such a way that they can simultaneously form the stiffening V in the edge area of ​​the bipolar plate, wherein the vent slots E are formed at regular intervals between the two sub-plates 1, 2.

[0081] In Fig. Figure 7 shows a schematic top view of the tool 5 for machining one of the partial plates 1, 2, both partial plates 1, 2, or the bipolar plate produced by means of the two partial plates 1, 2. At least one partial plate 1, 2 of the bipolar plate is arranged on the tool 5.

[0082] The tool 5 has three areas 5.1 to 5.3, which are preferably independently heatable and thus temperature-controlled. For example, it is possible to activate low-temperature soldering in a first area 5.1, to activate, in particular to polymerize, the adhesive as a joining material 4 in a second area 5.2, and to allow the joining material 4 to cure in a third area 5.3. Reference symbol list 1 first partial plate 1.1 First in-depth study 1.1.1 opposite section 1.1.1.1 Bulge 1.1.2 Wall 1.2 Area 2 second partial plate 2.1 Second in-depth study 2.1.1 opposite section 2.1.1.1 Bulge 2.1.2 Wall 2.2 Area 3 inner plate 4. Joining material 5 tools 5.1 first area 5.2 second area 5.3 third area An exterior surface D Sealing section D1 sealing material D2 further sealing material E vent slot H cavity I Inner surface L hole R Reservoir V-stiffening α Nesting corner β Free angle

Claims

[1] Method for manufacturing a bipolar plate of a fuel cell, comprising at least two partial plates (1, 2) which are connected to each other at least at the edges, wherein: a recess (1.1, 2.1) is provided around the perimeter of both partial plates (1, 2) and the partial plates (1, 2) are arranged such that a first recess (1.1) of a first partial plate (1) projects into a second recess (2.1) of a second partial plate (2), wherein an outer surface (A) of the first recess (1.1) is partially in contact with an inner surface (I) of the second recess (2.1); a joining material (4) is applied to the outer surface (A) of the first recess (1.1) and / or to the inner surface (I) of the second recess (2.1) in such a way that, after the partial plates (1, 2) are arranged together, the joining material (4) is located in a cavity (H) bounded by the outer surface (A) of the first recess (1.1), the inner surface (I) of the second recess (2.1) and by the contact areas, wherein the joining material forms a seal so that any gaps between the two partial plates (1, 2) are sealed against the environment; The recesses are provided in such a way that the subplates center themselves through the recesses when the bipolar plate is assembled, the angles of the walls (1.1.2, 2.1.2) of both subplates (1, 2) that laterally delimit the respective recess (1.1, 2.1) are predetermined depending on each other, so that at least a maximum dimension with regard to the projection of the first recess (1.1) into the second recess (2.1) is predetermined; and the contact areas are formed by the outer surface (A) being in contact with the inner surface (I) in the area of ​​the laterally bounding walls (1.1.2, 2.1.2) of both partial plates (1, 2). [2] Method according to claim 1, characterized by , that a solder and / or an adhesive is applied as joining material (4) to the outer surface (A) of the first recess (1.1) and / or to the inner surface (I) of the second recess (2.1). [3] Method according to any one of the preceding claims, characterized by, that a sealing material (D1, D2) is applied to a sealing section (D) which extends on a side of the first recess (1.1) of the first partial plate (1) and / or the second recess (2.1) of the second partial plate (2) facing away from the joining material (4). [4] Method according to claim 3, characterized by , that the sealing material (D1, D2) is hot-sprayed onto the sealing section (D) or sealing sections (D). [5] Method according to any one of the preceding claims, characterized by , that the partial plates (1, 2) are heat-treated to melt the joining material (4). [6] Method according to any one of claims 1 to 5, characterized by, that a number of vent holes and / or vent slots (E) are provided in an area (1.2, 2.2) of the first partial plate (1) and / or the second partial plate (2) adjacent to the first recess (1.1) and / or to the second recess (2.1), which are fluidically connected to the cavity (H) formed between the outer surface (A) of the first recess (1.1) and the inner surface (I) of the second recess (2.1) and the contact areas. [7] Bipolar plate of a fuel cell, comprising at least two subplates (1, 2) which are connected at least at the edges, wherein: the partial plates (1, 2) have a circumferential depression (1.1, 2.1) on their edges and the partial plates (1, 2) are arranged such that a first recess (1.1) of a first partial plate (1) projects into a second recess (2.1) of a second partial plate (2), wherein an outer surface (A) of the first recess (1.1) is in contact areas with an inner surface (I) of the second recess (2.1); a cavity (H) is formed between an outer surface (A) of the first recess (1.1), an inner surface (I) of the second recess (2.1) and the contact areas, in which a joining material (4) is arranged, by means of which the two partial plates (1, 2) are bonded together, the joining material forming a seal, so that gaps existing between the two partial plates (1, 2) are sealed against the environment; The projection of the first recess into the second recess creates a self-centering of the two sub-plates relative to each other, whereby the angles of the walls (1.1.2, 2.1.2) of both sub-plates (1, 2) that laterally delimit the respective recess (1.1, 2.1) are predetermined depending on each other, so that at least a maximum dimension with regard to the projection of the first recess (1.1) into the second recess (2.1) is predetermined; and the contact areas are formed by the outer surface (A) being in contact with the inner surface (I) in the area of ​​the laterally bounding walls (1.1.2, 2.1.2) of both partial plates (1, 2). [8] Bipolar plate according to claim 7, characterized by, that areas (1.2, 2.2) of the first subplate (1) and / or the second subplate (2) adjacent to the first recess (1.1) and / or the second recess (2.1) have a number of vent holes and / or vent slots (E) which are fluidically connected to the cavity (H) formed between the outer surface (A) of the first recess (1.1) and the inner surface (I) of the second recess (2.1) and the contact areas.

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